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What if mitochondria were originally Archaeans?

 
 
Reply Sat 8 Jan, 2011 04:20 pm
I've been trying to figure out, like many scientists, exactly where life originated from. It has led to one burning question for the moment, that I feel compelled to find an answer or discussion about: what if the earliest mitochondria were Archaeans that developed near thermal vents in the deep ocean?

Consider this: life began as a series of chemical reactions. Small bacteria, which began gathering in abundance in the newly condensed oceans, used photosynthesis to capture electrons directly from solar energy. This is an almost direct energy conversion and is ideal for any self-sufficient living organism.

These bacteria produce oxygen and, through decay of their inorganic material after death, phosphorous. The abundant hydrogen, oxygen, carbon and nitrogen within the water at this time began producing the raw organic and inorganic compounds necessary to create life: acids (like essential amino acids), lipids (and phospholipids), sugars (ribose and glucose), and proteins (like enzymes and even RNA itself).

I only recently began looking into Archaeans, but from what I can gather they, along with bacteria, are the first and simplest forms of life, and are naturally produced within the rich water.

This brings me to my point. All of this occurs before the first known ice age, which means solar energy, bacteria, and raw material are at an all-time high. Millions of tiny, filamentous bacterium coat the surface of the ocean floor, producing oxygen and sedimentary waste through natural reactive processes.

This sedimentary waste, rich in PO4, reacts with natural lipids to create phospholipid filaments that coat the ocean floor and begin collecting loose ribose sugars, pyruvic acid, and NADs. As the three components come together and are bound phospholipid material, they react to produce phenomena such as nucleotides, which link with the other ribose sugars and raw components -- bound by phospholipid filaments -- to produce a specific chain of amino acids called a protein.

One of these first proteins is raw ribonucleic acid, which acts as a prototype for even newer proteins such as adenosine triphosphate and the first RNA polymerases.

Now BOOM! The first known ice age. As the temperature of the water cools, the oceans grow much deeper in relatively short time as the excess water vapor in the atmosphere is condensed. Between this greater depth, the biological cloud of organisms in the early ocean, and thick ice, solar energy becomes scarce and bacteria may no longer survive through photosynthesis.

Without photosynthesis, the oxygen content of the water depletes. Bacteria and Archaeans, now faced with extinction on an individual level, join forces for the first time to produce mitochondrial bacteria -- or bacteria that may metabolize inorgnanic solids in addition to photosynthesis, depending on the need.

This new bacteria-mitochondria pair, still only considered a bacteria, paves the way for complex life by producing the first RNA, DNA, and proteins shared between two individual lifeforms. Thousands upon thousands of configurations occur naturally, while only the strongest and healthiest organisms and relationships prevail into successive generations.

I can't help but think... what if? What if the rest of the prototype organelles or structures within the cell were created as Archaeans or bacteria through "random" chemical reactions, were merely useful to other bacteria, and devoured to continue working within the membrane of the bacteria?

In this way, life truly becomes dog-eat-dog: the first stages of evolution occur when bacteria begins cannibalizing itself for energy. Basically.

Anyway, I'd just like a second opinion. For all I know this is common knowledge and/or has been proven otherwise outright, but the origins of life always seem to flabbergast scientists and I haven't yet read anything on this possibility.

What do you think?

PS: I only recently began studying this subject in any intensive detail (say, within the past 12-24 hours), so forgive me if my knowledge of chemical processes or the nature of bacteria/Archaeans is skewed or completely wrong.
 
View best answer, chosen by lieunacy
Setanta
 
  1  
Reply Sat 8 Jan, 2011 04:22 pm
I may be wrong about this, but i believe that i read long, long ago that the mitochondria were separate organisms in symbiotic relationships with the cells in which they had lodged. We have people here with good scientific knowledge--you should get a good answer to your proposition . . . maybe . . .
rosborne979
 
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Reply Sat 8 Jan, 2011 07:07 pm
@lieunacy,
At first glance your sequence of events seems a little out of order. Firstly, if bacteria are already dying and decaying, then the basics of genetics are already in place because bacteria are already very complex organisms.

lieunacy
 
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Reply Sun 9 Jan, 2011 02:21 pm
@rosborne979,
You raise a good point; I've been trying to work out exactly when DNA entered the picture. I'm almost certain RNA came first, but DNA almost certainly followed shortly thereafter -- it only makes sense.

Specifically, though, I was referring to Cyanobacteria -- the first life forms thought to exist. Truthfully, with so many events subject to conjecture it's almost impossible to discern exactly where and when the spark of life began, because the swampy, biotic waters of the early ocean combined with the surfeit of raw material -- both organic (carbon/nitrogenous) and inorganic -- and high temperatures provided by thermal vents (to "cook" the recipe) provided the perfect environment for uncontrolled chemical reactions.

In other words, what came first is hard to say because I believe almost all the necessary ingredients of life began as nothing more than a series of reactions which ultimately began with the Big Bang 13.75 billion (est) years ago.

In my mind, I believe the first "true" life began when two entities began a relationship to survive... something I imagine to be unprecedented in nature before organic reactions began to occur.

Yet, the difference between the stars in the sky and the marine life in our deep oceans is virtually negligible; life, then, is really only defined by the trust developed between multiple independent organisms to survive. In a word -- you could say it truly is love, right down to the organelles of a cell.

Which, to be frank, I believe were some of the first organisms to exist, which were then devoured by greater organisms until a self-sufficient, complex creature came into existence. That is why I asked the question, to explore that train of thought; were mitochondria independent organisms? How did the cycle begin? RNA and DNA must enter the picture in relatively short time, because evolution in the true sense of the word can't happen until heredity is established and protein sequences are stored for future recall. After all, you can't improve on something without consistent, identifiable traits.

Anyway, I'm ranting, but thank you for bringing that up. I'm still trying to piece it all together.

PS: I apologize if this post is all over the place, haha, I'm somewhat in a hurry and was trying to get it all down.
lieunacy
 
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Reply Sun 9 Jan, 2011 02:24 pm
@Setanta,
That would certainly back my hypothesis. Part of me wishes I'd gone to college; so many questions, so few people with knowledge on the subject (in my local area).
rosborne979
 
  1  
Reply Sun 9 Jan, 2011 02:39 pm
@lieunacy,
We have other threads on A2K which have covered this subject before. You might be interested in reading through them. I'll see if I can find one and provide a link.
0 Replies
 
farmerman
  Selected Answer
 
  3  
Reply Sun 9 Jan, 2011 03:32 pm
@lieunacy,
This has been hypothesized by Sagan and Margulis.
Early bacterial cells had acquired theur single genomes from compatible prokaryotes. The eukaryotes integrate complete genomes to form individulaseg, Plant cells show us that they have at least 4 separate and integrated genomes
1a motile form(the "chimera form")(Thermoplasmidia?-not sure of the DNA of this but MArgulis and Sagan used it in their model)
2protein synthesizing archeobacterium
3oxygen respirating protobacteria that became the mitochondrion of a cell
4A cyanobacterium that became the chloroplast.

Margulis theory (now,) then it was a hypothesis, came to be in about 1998 and was published into a short piece called "Acquiring GEnomes" in 2002.
Im sure its available through U of Mass where she 's an EMeritus in the geology dept.
farmerman
 
  1  
Reply Sun 9 Jan, 2011 04:23 pm
@farmerman,
Quote:
This has been hypothesized by Sagan and Margulis.
Early bacterial cells had acquired single genomes from compatible prokaryotes(this has been partially underpinned by fossil evidence from the fine sediments of the ISua Formation). The eukaryotes integrate complete genomes to form individuals ,. FOR EXAMPLE, from genomics, Plant cells show us that they have at least 4 separate and integrated genomes
1a motile form(the "chimera form")(Thermoplasmidia?-not sure of the DNA of this but MArgulis and Sagan used it in their model)
2protein synthesizing archeobacterium
3oxygen respirating protobacteria that became the mitochondrion of a cell
4A cyanobacterium that became the chloroplast.

Margulis theory (now,) then it was a hypothesis, came to be in about 1998 and was published into a short piece called "Acquiring GEnomes" in 2002.
Im sure its available through U of Mass press where she 's an EMeritus in the geology dept.




YYARGHHHH, Ive engaged is some ipsedixitism because nobody'd understand what the hell I was saying (Im not a friend of "proper spelling")
0 Replies
 
lieunacy
 
  1  
Reply Wed 12 Jan, 2011 11:13 pm
@farmerman,
I'll have to look a bit more into the things you mentioned. I'd already accounted for the archeobacterium (Archaeans?) and oxygen-respirating protobacteria, and the cyanobacteria -- being a photosynthetic organism -- only makes sense.

The motile form/Thermoplasmidia I'd not heard of before, but I did google the latter the other day. It makes sense at a glance; hopefully I can piece all of this new info together when I have the time to sit down and research.

Thank you, my friend. Have a good one.
0 Replies
 
 

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